Petri dish



FIG. 1 is a bottom view of a petri dish showing my new design;

FIG. 2 is a rear view thereof;

FIG. 3 is right side view thereof;

FIG. 4 is front view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a top perspective view thereof.

The broken lines shown in FIG. 1 are included for the purpose of illustrating the edge of the internal wall of the petri dish that forms no part of the claimed design. 

The ornamental design for a petri dish, as shown and described. 